The present invention generally relates to a slip clutch assembly and, in particular, relates to such an assembly wherein the rotated element remains subjected to a torque after the motive force is removed.
In general, a slip clutch is used when the applied force, usually rotational in nature, is not to exceed a preselected torque or when the rotation imparted to a member being rotated is not to exceed a particular angular distance.
One particularly demanding application of mechanisms of this nature is in the operation and control of optical elements such as those used in analytical instruments. A specific application is the redirecting of a precisely aligned light beam either by interposing a mirror in the path of the beam or by rotating a mirror from one angular position in the beam to a second angular position in the beam. In such precisely aligned arrangements it is important to avoid mechanically shocking the optical elements as this could easily result in substantial misalignment thereof.
A conventional system usually includes an electric motor solenoids and/or pneumatic cylinders. However, such systems are difficult to modulate and control. Such systems also frequently respond too rapidly and consequently impart mechanical shocks to the elements. Another commonly used mechanism includes the use of a combination of springs and switches. The springs are positioned in the drive train of the motor to maintain the rotated member in position after the motive force is removed by means of the switches. To date these latter mechanisms have been mechanically complex, expensive and quite difficult to adjust.
In view of the above, what is clearly needed is a slip clutch assembly which is inexpensive, mechanically simplified and accurate.